In a new discovery, researchers have found that lasers can safely replace years old quartz technology used in wristwatches or to transmit reliable signals to radios.

In a new discovery, researchers have found that lasers can safely replace years old quartz technology used in wristwatches or to transmit reliable signals to radios.

In lieu of a crystal, researchers at California Institute of Technology (Caltech) have developed a method to stabilise microwave signals in the range of gigahertz using a pair of laser beams as the reference.

"Our new method reverses the architecture used in standard crystal-stabilised microwave oscillators - the 'quartz' reference is replaced by optical signals much higher in frequency than the microwave signal to be stabilised," explained Kerry Vahala, a professor of information science and technology and applied physics at Caltech.

For nearly 100 years, these oscillators have relied upon quartz crystals to provide a frequency reference.

Quartz crystals "tune" oscillators by vibrating at relatively low frequencies - those that fall at or below the range of megahertz, or millions of cycles per second, like radio waves.

However, future high-end navigation systems, radar systems and even consumer electronics will require references beyond the performance of quartz.

In the new method called electro-optical frequency division, the optical reference used by researchers is a laser that looks like a tiny disk.

"At only six mm in diameter, the device is very small, making it particularly useful in compact photonic devices - devices powered by photons instead of electrons," said co-author Scott Diddams, a physicist at Maryland-based the National Institute of Standards and Technology.